01 - In a medium saucepan, combine cranberries, sugar, and water.
02 - Bring to a boil over medium-high heat, stirring occasionally.
03 - Reduce heat to low and simmer for 15 minutes, or until the cranberries have burst and the mixture thickens slightly.
04 - Remove from heat. For a smooth syrup, strain through a fine mesh sieve into a bowl or jar, pressing to extract as much liquid as possible. Discard solids.
05 - Stir in lemon juice and vanilla extract if desired.
06 - Let cool; the syrup will thicken as it cools. Store in the refrigerator for up to 2 weeks.